Fluid borne noise generated within a pressurized hydraulic system which uses a pump such as an automotive power steering system, can cause undesired noise and vibration. The oscillating pressure ripples generated by the hydraulic pump are carried within the hydraulic hose and tubing and cause other components to vibrate and emit noise. The use of a tuning cable mounted within a fluid conveyance hose to attenuate these pressure oscillations is known in the art with a description of such a system in U.S. Pat. No. 3,323,305 entitled Attenuation Device and issued to G. Klees on Jun. 6, 1967. The fluid noise reduction structure of the prior art comprises a flexible metal tube, called a tuning cable, that is placed inside a section of hydraulic hose. In the alternative, the tuning cable can be made of an engineered plastic such as PTFE or nylon or some other suitable material or combination of materials. The tuning cable can have holes formed along its length to increase the level of attenuation of the pressure pulses and hence, the level of generated noise. The length of the tuning cable must be specifically selected to provide the highest level of attenuation depending on the frequencies generated by the pump and the natural vibration frequencies of the various components. Sometimes this can be empirically determined but more often, trial and error is used to determine the correct length of the tuning cable along with the location and size of any holes or apertures along its length. Thus, it would be desirable to have a development system that would permit the tuning cable to be easily changed. The prior art systems require that a new hydraulic hose be made using each revised tuning cable which is time consuming and expensive.
The tuning cable can be spirally wound metal wall with a discontinuous wall construction that results in a distributed leakage along the length of the tuning cable. Or, it can be made of a continuous tube or of a continuous tube that has apertures formed along its length. The tube can be made of metal or of a suitable plastic material. The fitting used at the end of the hydraulic hose to attach the tuning cable varies depending on the type of material and wall structure that is used for the tuning cable. If the tuning cable is made of a plastic tube material, the tube can be slipped over a barbed end formed on an extension from the connector fitting. The hose is then attached to the connector fitting using a crimped socket.